Alternating-current signaling apparatus



l 1,482,558 Feb 5 4 B. P. HAMILTON ALTERNATING CURRENT SIGNALINGAPPARATUS Filed Sept. 26 1919 3 Sheets-Sheet 1 INVENTOR.

BBHamz'lZb/z A TT RNEY v Feb. 5; 1924. 1,482,558

B. P. HAMILTON ALTERNATING CURRENT SIGNALING APPARATUS a4 Bag. 5

filler }NVENTOR.

BJ Ham z'lzan l A TORNEY.

Feb. 5 1924.

' B. P. HAMILTON ALTERNATING CURRENT SIGNALING APPARATUS Filed Sgpt. 261919 3 Sheets-Sheet 3 m an L :r

I INVENTOR. B]? Hamilton A TORNEY Patented Feb. 5, 1924,

umrsosrArEs PATENT OFFICE.

BAXTER. P. HAMILTON, OF BRO OKLYE, NEW YORK, ASSIGNOR TO .AIKERICANTELE- IHONE AND TELEGRAPH COMPANY, A CORPORATION OF NEW YORK.

ALTERNATING-CURRENT SIGNALING APPARATUS.

Application iiled September 26, 1919. Serial No. 326,554.

To all whom it wmy mm .Be it known that I, BAXTER P. 'H-AnrL'roN,residing at Brooklyn, in the county of Kings and State of New Yorlghaveinvented certainlmprovements in Alternating-Current Signaling Apparatus,of which the following is a specification.

This invention relates to transmission 7 systems' 'and more particularlyto transmis- 10 sion systems inwhich Morse signals, telephone signalsand carrier currents are simultaneously transmitted over acommonCircuit. T

One of the features of the invention resides'in the provision of meanswhereby the transmitting and receiving apparatus of a carrierchannel'superposed on a composited telephone line may be renderedconjugate with respect to' each "other.

Another feature of the invention resides in the provision of, aiiltering arrangement, for separating the telephonic frequencies fromthe carrier and Morse frequencies.

A still further feature of the invention is the provision of a system offilters, so applied to the side circuits of a phantom system in whichthe side circuits are composited for Morse operation and are alsoutilized for transmitting carrier frequencies, that the filters in theside circuits act together to form similar filters in the phantomcircuit. 7 v

' These features, together with other char acteristics of the inventionmore fully hereinafter appearing, may be fully understood from thefollowing description when read in connection-withthe accompanyingdrawing, in :which Figures 1 to 5 inclusive illustrate circuit diagramsembodying five differarrangement of fil transmission. of Morse. signals.In order to superpose acarder c nnel upon the line. tuned bridges TB anu'iB are associated 7 with the; line at the terminal station ductivelycoupled with the tunedlu ent forms of the invention, while Figure thepurpose of utilizing the line for the plicable'not only to the arraemcnt is the transmitting circuit TC, including transmitting apparatusconventionally n1d cated as an alternating current generator and atransmitting key K. A receiving circuit, RC, is also inductively coupledwith the tuned bridge TB, said receiving circuit including receivingapparatus conventionally indicated as an alternating current receivingrelay RR. In order that the transmitting and receiving circuits'rnay berendered conjugate with respect to each other; so that electricaldisturbances in the one will not affect the other these circuits arecoupledto each other and to an artificial line MN, through a balancedtransformer 11'. Corresponding transmitting and receiving apparatus isassociated with the tuned bridge TB at the station B, said apparatusbeing designated by the san'ie reference characters primed.

In order to prevent the Morse and carrier frequencies from'beingtransmitted to terminal telephone apparatus which may be associated withthe jacks J and L filters FS and FS' are inserted in the telephonecircuit between the terminal jacks and. the composite apparatus GK andUK as illustrated. ,These filters are of the general type illustratedand described in the Uj patcuts of George ,A. Campbell. Serial Nos.1227,1l3aud 1.227.114; dated lllay 22. 1917, 'aud,'as described in s .dpatents. earl) '-ousists of a plurality of sections, each sectionincluding seriesand shunt impedance ele 'ments. For the purposes of thepresent inventioi'i these shunt and series impedance elements are sodesigned that the filter freely transmits a band of frequenciesextending over the voice range; while suppressing: carrier and Morsefrequencies.

Where it is desired to utilize the trans mission line as the sidecircuit of a phan tom system. it may be provided. with phan tom coils PCaud PC. with phantom taps such as 12, '12. extending from the mid'points of one ofthe windings of each of the phantom coils. tothephantoni circuit The complete phantom arrangement for a line. such asthat of Figure 1. may be more clearly understood from the diagram shownin Figure 6.- which. it will be understood. is apa t of Figure 1. but tothe modified arrangements shown in Figures 3, 4 and 5. In Figure 6. ML'andiw L' designate telephone lines connection of the relay RR at thestation A is such that it is unaffected by energy trans mitted from thelocal transmitting apparatus, but is responsive to energy incoming fromthe line. The relay HR at the station B is of course connected in thesame manner and is therefore unresponsive to energy transmitted byclosing the key K at station B. The filters FSand FS, as beiiore,prevent the transmission of carrier current to the terminal telephoneapparatus.

Still another modification is shown in I Figure 3, in which the mainline ML is provided with composite apparatus (IX and GK, and broad bandfilters FS and FS, as before. It Will be understood, of course, that thefilters FS and FS may be phantoined in the manner indicated in Figures 1and 4. Tuned branches TB and TB are bridged across the line ML atstations A and B respectively, and these bridges are associatedinductively through transformers 20 and 20 with carrier circuits CC andCC.

Each carrier circuit includes a differential relay as shown at DR andDR. The differential relay DR compriseswindings 30,31,

' 32 and 33, between the midpoints of which a transmitting apparatusconventionally indicated as a generator'G and transmitting key K isconnected. A balancing network or artificial line MN is connected towindings relay is not energizedand consequently the One armature 34thereof is not actuated.

half of the energy from the generator G is transmitted to the artificialline MN and the other half flows over the circuit CC through thetransformer to the tuned bridge TB,

from which itis transmitted over the line ML and selected by the tunedbridge TB at the station B. The alternating current is then transmittedthrough the transformer 20 to the carrier circuit CC and as the currentflows in series through the tour wind- "'ings of the difl'erential relayDR, said differential relay is actuated, so that the arm-a.- ture 34operates. Transmission over the line ML may simultaneously take place inthe opposite direction by actuatingthe key K.

Figure 4fillustrates a modification of the invention arranged to operateon a halt duplex basis. The arrangement of the coinposite sets GK. andCK. the filters FS and FS and the tuned bridges TB and TB are the sameas described in connection with the previous figures. It will beunderstood, of

course, that the filters and FS may be arranged for phantom operation asdescribed in connection with Figures 1 and 6. At station A the receivingcircuit RC inductively coupled to the tuned bridge TB through atranstorn'ier arrangeu'ient comprising windings 40 and 41. The receivingcircuit in cludes an alternating current receiving rc lay RR which inturn controls the local circuit of a relay 42, which controls the sounder S. The transmitting circuit TC is in ductively coupled with the tunedbranch TB through an autotransformer arrangement comprising Winding 41.Said transmitting circuit includes an alternating cur rent generator G.Both the transmitting circuit TC and receiving circuit RC are controlledby the contacts of a relay 43 under the control of the sending key K. Atthe station B the arrangement of parts will in practice be identicalwith those at station A, but for simplicity the details of the receivingcircuit R0 are not shown and in connection with the transmitting circuitTC only a sendin kev K and a enerator G are indicated in. series, thedetails or the con trolling arrangement being omitted.

The operation is as follows:

In transmitting from'station A to station B, the key K is actuatedthereby energizing the relay 43, which attracts its armature 44. therebyopening contact 45 of the receiving circuit RC and at contact 46completing the receiving circuit through a 12,000 ohm resistance 47.This resistance is Provided for the purpose of reducing the amount oflocal transmitting energy admitted to the receiving circuit RC throughthe transformer 40. 41, so as to prevent overloading the receiving relayRB. The armature 44 also closes the transmitting circuit TC at contact48. so that alternating current energy from the generator Gr istransmitted through autotransformer winding 41. to the tuned bridge TB,said energy being then transmitted over the main line ML and selected bythe tuned bridge TB at the receiving station B. This energy is thentransmitted through the transformer comprising windings 40 and 41 to thereceiving circuit RC.

Should the operator at station B desire to break in while the operatorat station A is speaking, the sending key K at station B will beactuated, thereby transmitting alter nating current to the tuned branchTB over the line ML to the tuned branch TB at sta tion A. It will benoted that as the operator at A is manipulating the key K, the relay BRwill be energized when the key is closed and de-energized each time thekey is opened, thereby causing the actuation of the sounder S throughthe relay 42.. When the alternating current from the distant station istransmitted from the tuned branch TB through the transformer 40, 41 tothe receiving circuit RC in response to the actuation of the key K, atthe station B, as just described,.

the relay BR will not release when the key .I\ is released, so that theoperator at A. will at-once observe that the sounder is not respondingto the signals transmitted by the hev K at station B desires, for somereason, to transmit a message. The operator at A will then permit thekey K to remain open, so

that the circuit RC will remain closed over.

the contact 15, the resistance of the receiving circuit RC being); thusrendered sufficiently low so that signals from the distant station willactuate the receivlng'relay RR.

An arrangement somewhat similar to that of Figure 4 is illustrated inFigure 5, except that in this case an improved means for amplifying anddetecting the received alternating current is illustrated. The tunedbranches, the composite set and the filter ar rangement are the sameinthis case as in those previously describedythc filters, asbefore,being arranged for phantom operation as described in connection \viththeFigures 1 and 6. The sending apparatus at the station A is schematicallyindicated as comprising a circuit TC" .Lincludini: a transmitting key. Kand an alternating current generator G. It will be understood, however,that this sci'iding circuit will in practice be identical with: thatshown at station A of Figure e. The receiving apparatus at station A isnot-illustrated, but will be identical with that hereinafter describedat station. Ii. The sending apparatus at sta tion B is not illustrated,but, as in the case of station A, will he identical to that illustratedin Figure 4; The receiving apparatus at StationB comprises a receivingcircuit RC connected to the input ot a-three-element vacuum tubeamplifier VA, the output of which is connectedthrough a trans former tothe input circuit of a threeelement vacuum tube detectorVD',in whoseoutput circuit is arranged a receiving relay 35R and, if desired. anammeter.

The operation of this circuit is as follows:

Upon actuating the key K alternating car riier currents from thegenerator'G are transmitted to the tuned branch. TB and thence over themain line 1WD to the tuned branch TB from which they aretransmitted tothe receiving-circuit RC and impressed upon the amplifier V A. Afteramplificatiom the amplified alternating currents are impressed uponthedetector VD which operates to 'de tect the signals in a well-knownmanner, so as to actuate the receiving rcla v RR.

It will be obvious that the general principles herein disclosed maybeembodied .in many other organizations widely different from thoseillustratechwithout departing from the spirit of the invention asdefined in the following claims:

and will understand that the operator;v

-. paratu s conjugate. Withrespect toieach other.

. mew

What is claimed is: 1.In a signal ng system, a transmission circuit, atuned bridge across said ault;

transmitting and receivingapparatus, as-

soci ated with said transmission ,circuit only through said bridge, and-means,for.maintaming SfllClt. ansinittmg and receivury ap- 2'. In asignaling system a;

circuit, a tuned bridge across said circuit,

transmitting and receiving apparatus associated with said transmissioncircuit only through said tunedbridge, and means for renderingsaidtransmitting. and receiving apparatus conjugate with respect to eachother, said means comprising an artificial line associated with saidtransmitting and receiving apparatus. i

3. In a signalingsystem, atransmission circuit, atuned bridge .acro.saiclciipiritf transmitting and receiving apparatus associated with 1said transmission circuit, by being inductively, coupled-l to;said-b1:idge only. and means for rendering said{transmitting and receivingapparatus conjugate I with respect to each other.

e. In a s gnallng system, a transmission circuit, tuned bridge acrosssaid circuit,

.tr ansmittingand receiving apparatus assoc1ated with said transmissioncircuit by being inductively coupled to said tuned bridge only, andmeans for renderingcsaid t l-ansmitting andreceiving apparatus conjugatewith respect to. each other, said means comprising an artificial lineassociated with.

said transmitting and receiving apparatus.

; 5;- In a signaling systema telephone .transmission line includingtelephone sets. composite apparatus associated .therewith for superposmg.Morse signals thereon, atuned bridge across said line. transmitting;and re ce ving apparatus associated with' said br dge, and means forrendering saidtransmittingand receiving apparatus conjugate with respectto eachv other. i i

6. In a signaling system. a telephone transmission line 'includingtelephone sets, composite apparatus. for superposingMorse sig na ls onsaid line. a tuned bridge across said line, transmitting a nd receiving;apparatus associated with said line, and .rneans for rendering saidtransmitting andreceiving ap}paratusconjugate with respect to ,-ea-ch oter.

7 In a signalingsystern, a telephone transmission line includingtelephone sets, composite apparatus for superposing Morse signals onsaid line, a tuned bridge across said line, transmitting and receivingapparatus inductively coupled to said tuned bridge, and means forrendering said transmitting and receiving apparatus conjugate withrespect to each other.

9. In a signaling system, a telephone transmission line, terminaltelephone apparatus associated therewith, composite apparatus associatedwith said line for superposing Morse signals thereon, a tuned bridgeacross said line, transmitting and receiving apparatus associated withsaid bridge, means for rendering said transmitting and receivingapparatus conjugate with respect to each other, and broad band filtersbetween the terminal telephone apparatus and said composite apparatus,and a tuned bridge for freely transmitting telephone frequencies, whilesuppressing Morse signals and carrier frequencies.

10. In a signaling system, a telephone transmission line, terminaltelephone apparatus associated with said transmission line, compositeapparatus associated with said line for superposing Morse signalsthereon, a tuned bridge across said line, carrier current transmittingand receiving apparatus associated with .said bridge, and broad bandfilters included in said line, between said terminal telephone apparatusand said composite apparatus and the tuned bridge, for freelytransmitting telephonic frequencies, while suppressing Morse signals andcarrier frequencies.

11. In a signaling system, a pair of telephone side circuit transmissionlines, terminal telephone apparatus associated with said lines,composite apparatus associated with said side circuits for super-posingMorse signals thereon, carrier current appa ratus associated with saidside circuits, phantom connectionswhereby said side circuits togetherconstitute a phantom transmission line, broad band filters in said sidecircuits between the terminal telephone ap paratus and said compositeapparatus and carrier apparatus for freely transmitting telephonicfrequencies, while suppressing Morse signals and carrier frequencies,and phantom connections between the corresponding filters in the twoside circuits, whereby the two side circuit filters constitute a filterin the phantom circuit for freely transmitting telephonic frequencieswhile suppressing carrier and Morse frequencies.

12. In a signaling system, a transmission line, a tuned bridge acrosssaid line, a transmitting circuit and a receiving circuit, eachassociated with said transmision circuit by being inductively coupledwith said tuned bridge only, an artificial line and inductiveconnections between said transmitting and receiving circuits and saidartificial line, whereby said transmitting and receiving circuits arerendered conjugate with respect to each other.

13. In a signaling system, a transmission line, a tuned bridge acrosssaid line, a circuit inductively coupled with said tuned bridge, saidcircuit including a receiving relay having balanced windings,transmitting apparatus connected to mid-points of said windings, and anartificial line associated with said receiving relay and transmittingapparatus.

14. In a signaling system, a telephone transmission line includingtelephone sets, composite apparatus associated therewith for superposingMorse signals upon said transmission line, a tuned circuit bridgedacross said line, and a receiving circuit associated with said tunedbridge, said receiving circuit including vacuum tube amplifier foramplifying received signals, and a vacuum tube detector for detectingreceived signals.

In testimony whereof, I have signed my name to this specification this25th day of September 1919.

BAXTER P. HAMILTON.

